Internet Protocol (IP) Television (IPTV) is a technology that distributes video content to subscribers by transporting video content using IP data streams over a packet distribution network. The content data streams of an IPTV distribution network, which may include a variety of TV channels, on-demand movies, and other content, are streamed from video servers toward the subscribers. The video content data streams are transported over one or more network elements (which may operate as channel selection points) between the video servers and the subscribers. In IPTV distribution networks, the video servers and channel selection points are typically arranged in a hierarchical manner, with video servers at the top of the hierarchy and subscribers at the bottom of the hierarchy, and one or more levels of channel selection points between the video servers and subscribers.
In IPTV distribution networks, in order to request a particular channel available from a video server, a subscriber initiates a channel request to a channel selection point, beginning with the channel selection point closest to the subscriber location. If the channel selection point closest to the subscriber location cannot serve the request (i.e., the channel is not available at that channel selection point), that channel selection point forwards the subscriber request upstream in the hierarchy of the network elements of the IPTV distribution network (i.e., toward the video server). The channel request from the subscriber continues to be forwarded upstream until reaching a network element (i.e., another channel selection point or a video server) that is able to serve the request. The network element serving the request streams the requested channel to the subscriber.
IPTV distribution over provider networks attempts to bring a full range of IPTV channels from a video server that is the source of the IPTV channels to a channel selection point that is as close as possible to the subscriber locations. Since IPTV distribution networks are typically hierarchical networks, the closer the channel selection point (from which a subscriber request for a television channel is served) is to a video server from which the requested television channel is available, the more problematic the IPTV distribution network becomes.
First, since IPTV distribution networks typically include multiple hierarchical levels, and the number of channel selection points at the different hierarchical levels increases in the direction from video server to subscribers, channel selection points closer to the video servers typically require higher bandwidth than channel selection points closer to the subscribers (i.e., the channel selection points closer to the video servers support more television channels than the channel selection points closer to the subscriber because the active television channels accumulate toward the video server). Due to economic reasons, IPTV distribution network operators cannot afford the link capacities required in order to deliver all available channels from the video server to the numerous channel selection points lower in the hierarchy
Second, for a channel selection request served by a channel selection point farther from a subscriber, the signaling delay between the subscriber and the channel selection point increases, typically resulting in unacceptable channel switching performance. Furthermore, this unacceptable channel switching performance may, in turn, encourage the subscriber to continue to issue requests for other channels before the previous channel requests have been completed. These additional requests for other channels that are issued before the previous channel requests have been server further exacerbate the channel switching performance problems.
Disadvantageously, channel selection points are currently devoid of any intelligence regarding which channels should be available from the channel selection points. As a result, channel requests often cannot be served by the channel selection point closest to the associated subscriber, thereby resulting in increased reaction times required by the network in order to react to channel selections, inefficient channel replacements (i.e., inefficiency in selecting which channel to drop if multiple channels are provided to the subscriber), significant increases in signaling overhead, and other problems which result as channel selection points from which subscribers are served move away from the subscriber locations.